Bacteria Recover Tin From E-Waste

A team at Coventry University, UK have demonstrated the potential to recover tin from e-waste using bacteria. The team’s initial results demonstrate that tin recovery from a printed circuit board (PCB) sample can reach 100%.

E-waste is the fastest growing waste stream in the world, but only 17% is documented as recycled. Circuit boards in this e-waste may typically contain up to 3% tin, but recovery can be challenging. Cost-effective extraction of tin is therefore essential in adding value to e-waste, moving towards a more circular economy and supporting future tin supply. Tin in solder represents around half of the world’s annual tin use.

In their latest research, the team added double sided gold-tin connectors to a leachate solution that contained bacteria at 30⁰C. The bacteria oxidised the tin to produce soluble tin compounds that can be recovered from the solution. In one set of experiments, 100% of the tin was recovered from the sample after 11 days. This cutting-edge bioleaching research by Coventry University represents a low-energy, sustainable solution to tin recovery from e-waste.

Since November 2019, the team have partnered with UK IT life-cycle service market leader N2S. The UK Department for Environment, Food & Rural Affairs (DEFRA) and other large electronic manufacturers in the UK have also expressed interest.

ITRI View: Bioleaching is a natural, green process that has been used in the mining industry for years. Applications of bioleaching to so-called ‘urban-mining’ are currently rare but its low-energy, low-waste credentials are of great interest amongst emerging tin recovery approaches. The team’s established commercial partnerships and funding put them in a strong position to adapt their bioleaching strategy to industry demands. If the process can be scaled up to tonnes of e-waste whilst maintaining high tin recovery rates, this technology may have very significant new potential.

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